A118629 Number of n-digit integers with decimal digits in increasing order.

10, 36, 84, 126, 126, 84, 36, 9, 1

Offset: 1

Author

Zak Seidov, May 09 2006

Keywords

• fini
• full
• nonn
• base

Comments

There are precisely 512 such numbers, see A009993.

Examples

			a(2)=36 because there are 36 two-digit integers whose decimal digits are in increasing order (see A009993): 12, 13, 14, 15, 16, 17, 18, 19, 23, 24, 25, 26, 27, 28, 29, 34, 35, 36, 37, 38, 39, 45, 46, 47, 48, 49, 56, 57, 58, 59, 67, 68, 69, 78, 79, 89
		

Crossrefs

Cf. A009993.

Formula

a(1)=1, at n>1: a(n)=binomial(10, n)(1 - n/10)

Extensions

Edited by Charles R Greathouse IV, Aug 05 2010